The field of the invention is vision systems that acquire and display a series of image frames, and particularly, vision systems such as those used to enhance night vision.
Night vision systems employ cameras that are sensitive to wavelengths such as infrared (“IR”). The image frames that are produced may be displayed alone in sequence to provide a moving picture of a night-time scene captured by the camera, or the IR image frames may be combined with image frames acquired at optical wavelengths to enhance the optical image frames.
Night vision systems typically employ heavy image intensifier systems. Although image intensifiers can increase brightness and provide modest improvements in detected signal-to-noise ratio (“SNR”) through amplification or spectral changes in the light incident on a detector, they cannot improve on the SNR provided by the light emanating from the low-light-level scene. Thus, such vision systems characteristically produce images having a high noise content. These vision systems are also characterized by difficulties in depicting moving subjects and a changing scene that results from panning of the vision system, for example, from head motion. Such motion makes it difficult to filter noise from the image frames without losing significant information.
It would therefore be desirable to provide a lightweight, optionally non-intensified, system for night vision having an improved signal-to-noise ratio (“SNR”) without the loss of significant information in the image. Additionally, it would be desirable to provide a method for enhancing the visualization of static and moving objects in low light conditions.